SWG is taking place in a time, where the Empire is weakened, but still the undisputed ruler of the Galaxy. The Emperor outlawed the Jedi long time ago, and Darth Vader Hunted them to near extinction. So, if you go with the story, the best decision for the Dev's would have been, to just drop Jedi as an profession entirely, but that's of course something they can't do due to "market demand" so they came up with a system to limit the numbers of Jedi in game, to make them rare and mysterious.

You will not be able to just click "Jedi" while creating you character, enter the server and start swinging you Lightsaber. If they allowed that, the population would consist of 90% Jedi, yelling "I R00xx0r U W|tH mY L33T LOiGhT SAbR d00d".. (we don't want that, do we?). So, you will have to start off with a normal character in any profession, and hope you manage to turn him into a Jedi later. The main requirement will be getting Force Sensitive, and there are multiple theories how that will happen, which range from "assigned random at character generation" to the (in my eyes more realistic) "chars have invisible counter that increases/decreases with certain actions". The Dev's already made clear, they don't want the exact system to be known and you can be pretty sure, the time someone finds sure way to become FS there will be a patch to change it, so it will be pretty much random who will be blessed by being FS.

But, getting FS is the easy part. As soon as you are FS, you will get access to the Jedi skill tree. You still have to gain Jedi XP (through using you powers) and find a way to spend that XP for news skills, for instance through a teacher or visiting certain locations. Ultimately you will most likely get/notice you are FS pretty late in the game after already having trained up in different skills, but getting to any useful level of Jedi will most likely also require you to completely drop all other skills and concentrate on being Jedi.

Now here comes the real problem. You have to gain XP, and XP is usage based, e.g. you get better with blasters through using a blaster, so you get better with the force through using it. But doing so while other people are around will obviously reveal your Powers. As I wrote above, Jedi are actively hunted by the Empire, and killing an Jedi will most likely be the single most effective action to gain XP/Rank an Imperial can achieve.

So Jedi will act as some kind of Highlevel mobs for some and i am sure some ppl will specialise in hunting them. Any death will be very very bad for a Jedi since the dev's stated that Lightsabers can't be insured and I assume there will be additional penalties, like losing ForceXP or something there like.

It also was stated, that you will have to work quite hard to actually keep your powers, so you cant just build up to a certain level, stop using them for some weeks and expect them to be still there.

Also, I suspect Jedi to be absolute Solo characters, that will get more disadvantages from being grouped than not.
Life of a Jedi will be hard. And I mean REALLY HARD. Most Jedi will have to fight for pure survival. Being Jedi will plainly not be any fun for anyone but the most hardcore Roleplayers/Powergamers/Starwars fans, so that even of the very few that will get force Sensitive, only some will actually choose being Jedi, and even less will actually get somewhat powerful.

The next and more severe issue is, that Legion is an Imperial Faction, and Imperials hunt Jedi. The Emperor Disbanded the Jedi and wants to see every single one of them dead, because they are the only one that could eventually be a danger to him and Vader, so our job is plainly to kill any Jedi on sight.

and No, Dark Jedi are not really Imperial.

The Emperor and Darth Vader are Sith, another sect of (dark)Force users. Their codex only allows 2 at any given time to be Knowledgeable in the Force. Opposed to that, Dark Jedi are Jedi that have fallen to the Dark side of the force(duh). DJedi will most likely be even more Dangerous than regular Jedi, but also more seldom because they will be hunted by everyone (the imperials hunt them for being Jedi/force user, the Rebels will hunt them for being evil) and finding a way to "fall" also won't be that simple. I would expect anyone that manages to become a High level Dark Jedi to have a very lonely existence, and that they will function as a kind of super villain, with only one or two in existence at any given time. (think "Dragons in DaoC/EQ") ;)

So, I hope this will show you, that becoming Jedi is not really that desirable. You will have to give up most of the other stuff, that makes the game fun and still put incredible amounts of time into the game, just to be able to swing your lightsaber from time to time.

*waving finger* "You want to go home and rethink you desire to become Jedi" :-)

final note: Yes i mixed the confirmed stuff with a lot of my own theories, but i still think it's a pretty good overview of what to expect.